Carburetor with dash pot throttle control



Nov. 9', 1965 B. WALKER ETAL 3,216,707 CARBURETOR WITH DASH POT THROTTLE CONTROL Filed March 29, 1962 --iiiiiiii--" 25, A]

3 4 I23 25. a [62 3/ I INVENTORS (5 4 BROOKS WALKER By FRA IVK w. KERTELL 12 v ATTORNEYS United States Patent 3,216,707 CARBURETQR WITH DASH POT THROTTLE CONTRDL Brooks Walker, 1280 Columbus Ave., San Francisco 11, Calif., and Frank W. Kertell, Oakland, Calif.; said Kertell assignor to said Walker Filed Mar. 29, 1962, Ser. No. 183,629 3 Claims. (l. 261-65) This invention relates to the metering of fuel and fuel/ air mixture during acceleration and deceleration of internal combustion engines, particularly those used in automotive vehicles as controlled by the rate of throttle opening and closing and the rate of acceleration pump action.

Much attention has lately been given to smog control and to the extent to which automobiles tend to produce smog by exhausting unburned hydrocarbons into the atmosphere. Gasoline which has been fully burned has little tendency to aggravate the formation of smog, but exhaust fumes containing unburned hydrocarbons, carbon monoxide and other noxious products, can, under certain atmospheric conditions, produce a severe type of smog.

The tendency toward incomplete combustion is high during acceleration and deceleration of the automobile and is more pronounced during certain parts of those phases of the driving cycle than during other parts. The present invention relates to the control of the rate of throttle opening and accelerator pump action during acceleration and deceleration in a way that reduces some of the conditions which tend to result in imperfect combustion; the invention, therefore, tends to reduce the production of smog-producing agents.

Automobile engines are not, of course, designed solely in order to control smog. A very important problem confronting an engineer desiring to reduce the smogforming tendencies of automobile engines, is how to do so without adversely affecting the cars performance, to the point where driver acceptance is seriously impaired.

An important object of this invention is to enable the driver to obtain good performance from his car while substantially reducing the tendency of that car to exhaust smog-forming components, in the form of unburned hydrocarbons and carbon monoxide products.

Another object is to provide relatively smooth engine operation even when operated by a poor driver as far as rates of accelerator pedal action are concerned. A poor driver may pump the throttle excessively or open the throttle more rapidly than desirable for smooth car operation. This tendency is eliminated or reduced at the carburetor with applicants control between the foot throttle and the carburetor throttle action.

For example, the rapid and repeated opening and closing of the throttle and its interconnected accelerator pumps has tended to increase the production of smogproducing exhaust fumes. Many drivers, in order to be sure of fast (hot rod) start from a trailic stop light or a stop sign, go up and down on the accelerator pedal with their foot, several times, and the accelerator pump then sends an overly rich mixture into the engine. The fuel in the over rich mixture is not burned in its entirety and much of it is expelled as unburned hydrocarbon through the exhaust compared to the percent of unburned hydro carbons in the exhaust at normal cruises with a lean adjustment on the carburetor. The unburned hydrocarbon percentage in the exhaust during acceleration with a delayed opening of the throttle, even if the delay is only around 1 /2 to 3 seconds from closed to open on throttle pedal sudden tramp down will be much less than with a suddenly opened or rapidly pumped throttle butterfly. When thousands of drivers are cruising with a stationary throttle the engine is burning its fuel fairly well and not producing as much smog as when accelerating with a rapidly opened throttle or when the throttle is pumped rapidly with excess fuel supplied at each stroke by the usual acceleration fuel pump. When thousands of drivers are using similar or hot rod acceleration techniques, involving rapid throttle openings and closings they are adding to the production of unburned hydrocarbons and smog. However, simply removing the accelerator pump would not solve the problem, for then if a driver opened the throttle pedal rapidly or repeatedly in quick sequence (pumping the pedal) he would produce increased unburned hydrocarbons in the exhaust with resulting smog, by the engine being too lean on acceleration. A rapid closing of the throttle will result in the mixture burning too rich in the deceleration; this can be reduced by a slight delay in the closing rate of the throttle. Perhaps drivers can be trained to move the throttle pedal more slowly, following a prescribed acceleration pattern, of a 2 or 3 second opening period. An airplane pilot is trained to apply the throttle slowly. Such training of the millions of car drivers would require considerable schooling at great expense and many drivers would not abide with the schooling. Such drivers would continue to get bad smog producing performance from engines, because of their bad driving habits.

One of the objects of the present invention is to so meter the opening rate of the throttle that a driver who tramps down quickly on the accelerator pedal will not open the throttle faster than allowed by the dash pot. The driver will get a more even and smooth acceleration than he would get with an unrestricted throttle rate of opening. In other words, the present invention allows reasonable rate of opening action of the throttle valve-(and accelerator pump if needed). The invention compensates for bad driving habits in rapid throttle pedal opening by metering of the rate of throttle valve opening. The rate of throttle valve opening on tramp down of the throttle is taken away from the driver and put through an automatic mechanism that causes the engine to accelerate in a way that will give improved results by a graduated rate of resistance to throttle opening and a graduated rate of throttle opening. This control of the rate of throttle valve opening will reduce the unburned hydrocarbons exhaust emissions compared to an uncontrolled rate of throttle valve opening. With this graduated dash pot control of the variable rate of throttle opening which controls and distributes the accelerator pump discharge over more revolutions of the engine, than results from a suddenly opened throttle valve. A satisfactory rate of vehicle acceleration is achieved with this invention. Some control of the closing rate may also be desirable and a dash pot of the design shown in this invention will assist in accomplishing this goal and will result in a reduction in unburned hydrocarbons compared to a suddenly closed throttle valve if the idle fuel is not turned off on deceleration as in US. Patent No. 2,809,623 to F. V. Hall.

In deceleration a great amount of unburned gasoline and unburned hydrocarbon is often emitted from the exhaust due to incomplete full burning. This results from a wet manifold during cruise or acceleration before sudden throttle closing and the resultant sudden reduction of the oxygen to burn the fuel as well as the incomplete combustion taking place at the lower compression pressures encountered at high suction closed throttle operation.

Another object of the invention is to provide a system for metering the rate of throttle opening and the resulting acceleration and deceleration which can be adjusted to many types of automobile engines by the simple medium of changing a metering rod and/ or an orifice in the dash pot piston.

This dash pot may be used with a carburetor and linkage like that shown in US. Patent No. 2,809,623, to F. V. Hall, in which the soft linkage between the throttle pedal and the carburetor butterfly includes a spring or yielda'b le means which yields when the throttle pedal is suddenly depressed and the rate of throttle opening is controlled by the dash pot.

A Conventional carburetor is shown in this invention. However, a carburetor of suitable type which is improved by dash pot restricted rates of throttle opening may be used.

In this invention a novel dash pot structure is provided in which the movement of the dash pot controlled part (and therefore of the butterfly valve of the carburetor) is controlled and metered within the dash pot; itself in a simple, inexpensive, easily adjusted, relatively leak resistant type of construction. I

Another feature of this invention is the design of a dash pot with a non-stepped cylinder having a changed rate of control in one direction and a diiferent change-d rate of control in the other direction if two changed rates are desirable.

Another feature of the invention is to utilize the fuel from the float bowl to supply the liquid for the dash pot in such a way that the dash pot remains full even if the fuel is withdrawn from the float bowl.

The invention therefore relates also to a novel dash pot construction for operation of a metering device or any device that needs dash pot control.

Other objects and advantages of the invention will appear from the following description of a preferred embodiment.

In the drawings:

FIG. 1 is a view in elevation and partly in section of a unit incorporating the principles of the invention, showing a throttle rod, a carburetor, a dash pot, and linkages.

FIG. 2 is a view in side elevation and partly in section of the dash pot and control links of FIG. 1 showing the dash pot piston at the opposite end of its stroke from that shown in FIG. 1.

FIG. 3 is an enlarged view in section taken along the line 3-3 in FIG. 1.

FIG. 4 is an enlarged view in section taken along the line 4-4 in FIG. 1.

The drawing shows a throttle lever which is connected through a so-called soft link 11 that includes an elongated coil spring 12 to an accelerator pedal, not shown, or other well-known device. There may, of course, be cranks, return springs, and so on, acting on the throttle lever 19 or on the accelerator pedal, but these are so well known as not to require illustration. Choke wire 19 is connected to a crank 13 which pivots about a pin 14 and has an arm 14a. Rocker arm 15 is pivotally attached to a pin 1511 which holds the butterfly valve Min of the carburetor 18 at a faster idle during choke by contact with idle adjustment screw 10b. Choke butterfly is secured to shaft 9 in the usual way. Attached to the throttle lever 10 is link 16. Link 16 is attached to one end of rocker arm 26 that leads to and is pivotally attached at its other end to the upper end of piston rod 21 of a dash pot piston 22. Rocker arm is pivoted at pin 7 to the upper end of oscillating link 8. The bottom end of oscillating link 8 is pivoted to pin 6 which is attached to carburetor 18.

The dash pot piston 22 moves in a cylinder 23 which is divided into two portions by a partition 24 and has a closed lower end. The piston rod 21 passes through the partition 24 and upper cylinder end 25, clearance eing provided as needed. There may be an opening 26 with a spring flapper valve 27 acting as a check valve for communication from chambers 3%! to chamber 31 provided on opposite sides of the partition 24.

A metering rod 32 extends the full length of the inside of cylinder 23 through the partition 24 and through piston 22. Rod 32 is provided with a portion 33 that is flattened and a portion 33a that has a reduced tapered flattened portion to form a variable orifice diiferent at" different positions in piston travel with maximum resistance as the throttle valve starts to open. The rod 32 6X-' tends through an opening 34 through the piston 22 and the opening 34 is slightly larger than the rods diameter so that there is a sliding clearance. The upper end of the cylinder 23 is provided with a tube 35 leading to the fuel float chamber 36 where fuel from the fuel tank is stored in carburetor 18. This supplies liquid fuel at all times in the upper chamber 30 of the dash pot cylinder 23 and, by means of the check valve or clearance of parts, there is always a supply of dash pot fluid, namely gasoline or liquid carburetor fuel in the lower chamber 31 even if the carburetor float bowl were temporarily drained of fuel.

As a result of the dash pot, when the throttle pedal is either pressed down or is let up, the piston 22 must move in the cylinder 23 and its movement is opposed by the flow of gasoline or fuel in the lower chamber 31 past piston 22. This delays the movement of the throttle butterfly 17. However, it will be noted that because of the flat portion 33 and 33a on the metering rod 32 the resistance to rate of movement of the piston 22 in the cylinder 23 is not constant due to the variable orifice formed by the flat 33 being of less depth at the bottom of rod 32 than at its upper portion. Thus, with the piston 22 in the position shown in FIG. 1 at the bottom of the chamber 31, when it starts to move up, it will at first encounter considerable opposition to rapid motion due to the restricted passage between the piston hole 34 and the small flat 33b on rod 32 reduced resistance isencouraged in passing tapered flat 33a but as soon as the lower part of the piston 22 is above the tapered flat portion 33a of the rod 32 it will move upwardly more freely. It will, however, continue to be dampedbut at a lesser rate. By shaping the flat portion 33 to provide several portions thereof, at different depths, dif-' ferent rates can be provided at different parts of the stroke of the piston 22. When the piston 22 reaches the top of the stroke, the throttle butterfly 13a is essentially wide open. On the movement down of piston 22 it encounters a lower rate of resistance than when it started up. When it reaches the tapered fiat portion 33a the resistance gradually increases to even down the rate of closing. During the movement of piston 32 either up or down, past the flat portion 33 and 33a, as a result of tramp down of the foot throttle of foot off on decelerat ing the piston 22 is moved at a metered rate in accord ance with the known resistance to flow through the size orifice between rod 32 and hole 34 in piston 22 provided by the fluid in the lower chamber 31 and the force provided by the spring 12 of the soft link as a result of tramp down of the throttle.

A soft link in the throttle control is composed of stamping 11, collar 4, on rod 5 which is pivoted at turn end So to throttle lever 19. Set screw 4a secures collar 4 to rod 5. The foot throttle (not shown) is attached to end 11a of stamping 11. The varying pressure of spring 12 acting between collar 4 and end 11b of stamping 11 will provide a varying pressure on the dash pot resistance as the foot throttle is suddenly opened and this varying pressure due to spring 12 will affect the pressure acting on piston 22 of the dash pot and vary the rate of travel. It is desirable that the rate of opening of the throttle butterfly 1% on a sudden tramp down of the foot throttle be not less than 1 /2 or 2 seconds. The rate of closing should be the same or could be faster if a passenger and flapper valve were provided on piston 22 as in diaphragm 24. Oscillating arm 8 moves back and forth during the stroke of piston rod 21 so that piston rod 21 moves in line with piston 23. Pivot 7 oscillates as arm 7 oscillates and arm 15 oscillates between the motion of pin 16a attached to throttle lever 19 and the motion of pin 16b: attaching arm 16 to rocker arm 20.

Plug 4% in line with metering rod 21 allows easy re moval of rod 21 for changed metering characteristics. We have illustrated our invention in these various forms; however, many other variations may be possible within the scope of this invention.

To those skilled in the art to which this invention relates many changes in construction and widely diifering embodiments and applications of the invention will suggest themselves without departing from the spirit and scope of the invention. The disclosures and desciption herein are purely illustrative and are not intended to be in any sense limiting.

We claim as our invention:

1. A carburetor including a throttle valve, a dash pot, and a float bowl, means to supply fuel to said float bowl, means for supplying said dash pot with fuel from said float bowl, said dash pot including a cylinder therein having a piston slidably mounted therein, control means for said throttle including linkage means operatively connecting said throttle valve and said piston, fluid passage means extending through said piston, a metering rod mounted within said cylinder and extending through said fluid passage means, said metering rod having a variable cross-sectional area within the portion thereof traversed by said piston, said variable cross-sectional area being arranged such that said area increases as said piston approaches a position wherein the connected throttle is in its closed position, the portion of said cylinder in which said piston moves being mounted below the level of fuel in said bowl, and said control means for said throttle including a lost-motion force-transmitting means forming a soft-like connection therein.

2. The device of claim 1 wherein said dash pot cylinder is mounted in a substantially upright position.

3. The device of claim 2 wherein the second-mentioned fuel supplying means includes conduit means interconnecting said fuel bowl and the upper portion of said dash-pot cylinder.

References Cited by the Examiner UNITED STATES PATENTS 1,685,750 9/28 Pfau et al.

2,019,172 10/ Chandler.

2,090,246 8/37 Alexander 251-54 2,144,153 1/39 Henning 261 2,5 80,751 1/ 5 2 Fletcher.

2,695,153 11/54 Gillaspy.

2,703,705 3/55 Boiler.

2,732,038 1/56 Olson et a1.

2,807,457 9/57 Brueder.

2,809,623 10/57 Hall i 123-179 2,866,223 12/58 Von Dillen 188-96 X HARRY B. THORNTON, Primary Examiner.

GEORGE D. MITCHELL, HERBERT L. MARTIN,

Examiners. 

1. A CARBURETOR INCLUDING A THROTTLE VALVE, A DASH POT, AND A FLOAT BOWL, MEANS TO SUPPLY FUEL TO SAID FLOAT BOWL, MEANS FOR SUPPLYING SAID DASH POT WITH FUEL FROM SAID FLOAT BOWL, SAID DASH POT INCLUDING A CYLINDER THEREIN HAVING A PISTON SLIDABLY MOUNTED THEREIN, CONTROL MEANS FOR SAID THROTTLE INCLUDING LINKAGE MEANS OPERATIVELY CONNECTING SAID THROTTLE VALVE AND SAID PISTON, FLUID PASSAGE MEANS EXTENDING THROUGH SAID PISTON, METERING ROD MOUNTED WITHIN SAID CYLINDER AND EXTENDING THROUGH SAID FLUID PASSAGE MEANS, SAID METERING ROD HAVING A VARIABLE CROSS-SECTIONAL AREA WITIN THE PORTION THEREOF TRAVERSED BY SAID PISTON, SAID VARIABLE CROSS-SECTIONAL AREA BEING ARRANGED SUCH THAT SAID AREA INCREASES AS SAID PISTON APPROACHES A POSTION WHEREIN THE CONNECTED THROTTLE IS IN ITS CLOSED POSITION, THE PORTION OF SAID CYLINDER IN WHICH SAID PISTON MOVES BEING MOUNTED BELOW THE LEVEL OF FUEL IN SAID BOWL, AND SAID CONTROL MEANS FOR SAID THROTTLE INCLUDING A LOST-MOTION FORCE-TRANSMITTING MEANS FORMING A SOFT-LIKE CONNECTION THEREIN. 